1. Field of the Invention
The present invention relates to an information provision system for providing content information to a terminal device on a user side, a content information copying device, a user terminal device and a user management device for use in the system.
2. Description of the Related Art
In recent years, it has become possible to distribute an enormous data quantity of content by using a communication line owing to the progress of a communication technology such as the Internet and a data compression technique depending on digital signal processing. Thereby, a customer has become possible to receive a content distribution service for music, movies, games, etc., regardless of time and place. An information provision system for achieving this content distribution service has generally a configuration in that a customer desiring purchasing/viewing (hereinafter referred to as user) accesses to a content distribution center through communication terminal equipment to download desired content from the distribution center or receives a stream distribution.
However, in the present situation, even when the user accesses to the distribution center, there are many cases, for popular and topical content, that only an introduction thereof or an advertisement therefor is provided and content for viewing is distributed thorough a mail order of a medium with the content recorded thereon. This is because a copyright owner of the content (or copyright manager, hereinafter both concepts are generally referred to as a copyright owner in some cases) still fears to suffer tremendous damage caused by a copyright infringement such as illegal copying with respect to a distribution to a user terminal device using the communication line. Like this, in the content distribution service, a distribution of important content has been in an extremely inactive situation, because a problem in an illegal distribution becomes a fetter, even if the content distribution service is desired by the user or attractive in business.
Thus, recently, a technique to prevent the illegal distribution of content has been presented, in which an information storage medium and a user terminal device implement copyright protection on the basis of license information given from each license agency. This technique has been publicly known commonly as content protection for recordable media (CPRM) and Advanced access content system (AACS).
An information provision system for the content distribution service in order to achieve perfect copyright protection is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-350150. This system utilizes the aforementioned CPRM technique to implement the copyright protection on the basis of the license information given from the license agency in the information storage medium, the user terminal device, a content encryption device and a content key encryption device. The content distribution center manages the content in an encrypted state and realizes a wide variety of types of copyright protection which enables controlling a content illegal outflow from the inside and outside of the distribution center and authentication processing among each enterprise and each device.
However, in a conventional information provision system described above, encrypted content with an enormous quantity of data has been transmitted via the communication line, traffic volume on the communication line increases as the number of users increases; the increase becomes a possible trigger of communication interference as well as it causes taking a long time to download the content. And the impossibility of an acquisition of content information without a user registration causes the difficulty of the user registration.